Supervision device for variations of temperature



R. J. JORDI SUPERVI-SION DEVICE `FOR VARIATIONS OF TEMPERATURE Flled Aprii 11. 1954 .Qww @MAME WSWMUN L ff f RNEYS.

Patented Aug. 9, 1938 UNITED STATES PATENT OFFICE SUPERVISION DEVICE FOR VARIATIONS F TEMPERATURE- Application April 11, 1934, Serial No. 720,140 In France April 28, 1933 1 Claim.

It is often necessary to watch the temperatures of different points in a large space, say of the different places in works, docks, hotels, and so on, or the cabins, bunkers, holds, etc., of a ship;`

arms being disposed at the places to be Watched over and constituted by different metals the conductivities of which vary in' different Ways with the temperature. In such conditions, if the bridge is balanced for a determined temperature and if this latter changes, the resistances of both other arms will increase or decrease unequally [and the electric balancing will be destroyed; a 'current then ows in the galvanometer circuit and can be used either for actuating only an alarm signal or for energizing a relayactuating different alarm signals.

SO Such a relay must of course be very sensitive, and it has been proposed to use a single relay of that kind, a distributing device, continually moving, connecting it successively with the different bridges.

35 Such a system presents a Very serious drawback, the alarm signals are actuated for a determined Variation of temperature, as well if this latter has normal causes, as if it is produced accidentally.

For instance, if We consider a ship bound for tropical countries and sailing in winter out of a harbor in the Channel or North Sea, when sailing the atmospheric temperature will be very low, about Zero degrees centigrade or even lower,

and Wheatstone bridges must consequently be balanced accordingly. When the ship arrives in the tropical regions, the temperature in some places to be watched over can reach 35 centigrade or centigrade. It thus will be neces- 40 sary to adjust the bridges and relay in such a way that the alarm signals will be actuated only Yfor a temperature variation of at least 50 centigrade; but in such a case, in the beginning `oi her journey, when the ship is still in cold regions, an incipient fire will be indicated only when the increase of temperature shall have reached and then the re will have de veloped considerably and be more diilicult to extinguish.

56" It has been proposed for avoiding said drawback to use a supervision of Wheatstone bridges wherein the variable arms of one bridge are made with the same metal and disposed in places far from one another and the temperatures of which must normally always remain equal to each other. Referring again tothe same example of Y a ship, the places to be watched over shall be distributed in groups of two, the two places belonging to the same group being so chosen that under normal conditions they have always 5 substantially equal temperatures, and that they are so distant from one another that a lre happening in one of them shall have no influence on the temperature of the other. For instance, a group may comprise two cabins similarly dis- 10 posed: both on the deck orl both inside the ship, the one being astern, the other in the fore part, and both on the same side, port or starboard, in order to be similarly exposed to the suns rays.

In factories, hotels, ships, and the like, thel parts wherein there is the most risk of iires and which consequently must be the most carefully supervised, are the electric conductors or cables or groups of wires, which are frequently insulated with or are near combustible material and 20 the temperature of which may rise dangerously not only as a consequence of an incipient re in their neighborhood, but also in consequence of accident, such as a short circuit or overload occurring in the cable itself, which then becomes 25 the cause of a lire.

The single figure of the drawing shows diagrammatically and b-y way of example one form or embodiment of the invention.

l, 2, l, 2 are bundles of wires, disposed for 30 example within a sheath or conduit, or cables containing a plurality of conductors, and said bundles of Wires or cables are grouped in pairs in such manner that the two cables of one pair, say l and 2, are spaced from one another and 35 so that under ordinary conditions their temperatures will remain equal to one another, Since all of the various cables or bundles of Wires are mounted in exactly the same way, it will be` necessary to discuss in detail only the particular 40 cables l and 2.

Within the cables or bundles of Wires l and 2 and throughout the length thereof are disposed loops. 3 and 4 of auxiliary conductors, constructed of a material the resistance of which 45 varies rather extensively with changes in temperature, which are connected with resistances 5 and 6, so designed that the resulting Wheatstone bridge, the arms of which are the resistances 5 and 6 and the loops 3 and 4 respectively, will 50 normally be in balance. Said Wheatstone bridge comprises also a battery 'i and a sufficiently sensitive galvanometric relay 8, which are connected successively in the diagonals ofthe various bridges, the relay in turn being connected 55 successively with the corresponding alarm device belonging to the pair of auxiliary conductors with which the relay is connected at the time. These successive connections are made by 5 any convenient device, for example, that illustrated diagrammatically in the drawing. A motor 9 having a continuously rotating rotor actuates a plurality of switching means; for eX- ample, a disc Il of insulating material which is 10 provided with a conductive segment I2 continuously connected, by means of a slip ring I3 and a brush I4, with one pole or terminal of the battery 1; a brush I5, connected with the junction point between the resistance 5 and the loop 4, and similar-brushes for the other pairs of cables, bear on the edge of the disc II, and thus the battery is introduced successively into the diierent bridges, 3, 4, 5, and 5 3', 4', 5', and 6'-etc.

In a similar manner the winding of the relay 8 is introduced successively into the same bridges, by means of the disc I6. This disc is also made of insulating material and carries a segment 21 of conducting material upon which 25 bears a brush 28, connection being made to the segment 2l' by means of the slip ring 29 upon which bears the brush 3!) leading to the conductor 3l which makes connection with the winding 25 of the relay 8. Corresponding brushes I5 and 28 bearing on the discs II and I6 respectively provide connection through the conductors connected thereto with the Wheatstone bridge 3', 4', 5', 6.

It will be understood that the discs I9 and 2) 3@ are constructed in the same way as the discs II and I6 already described, these discs having the conductive segments 32 and 33 respectively which are connected to the slip rings 34 and 35 upon which bear the brushes 3S and 3l which ,are connected to the respective contacts I'I and `I8 of the relay 8 as shown. The conductors 23 and 24 which terminate in brushes 38 and 39 bearing upon the respective discs I9 and 2l] thus serve to put the alarm device 2l into service .when the bridge involving groups I and 2 be- `comes unbalanced in one direction or the other, while the brushes 38 and 39 leading through the conductors 23 and 24 to the alarm device 2| will serve to actuate said alarm in case the 50,-bridge involving I and 2 becomes unbalanced.

While only two bridges and two alarm devices have been indicated, it will, of course, be understood that in practice any desired number of such bridges and corresponding alarms will be 55 ,provided dependent upon the needs of the par- "ticular installation.

Of course, the switching means herein disclosed may be replaced by any other suitable means and the alarm devices also may be of any 60 suitable or convenient nature desired.`

` It is clear that if the temperature, say at some point of the cable or bundle of wires 2, should accidentally increase, due to an overload, ashort circuit or any other cause, the temperature (;5.`meanwhile remaining substantially constant "throughout the entire extent of the cable I, then when the auxiliary conductors 3, 4 and the resistances 5, 6 are connected with the battery 'I and the relay 8 to constitute a Wheatstone 70. bridge, said bridge will be out of balance, and r`the relay armature 26 will consequently assume one of its contact closing positions, wherein the battery 22 is connected with the alarm device 2l which will thus indicate that an abnormal increase of heat requiring investigation has occurred in the cable at 4.

As said above, the temperature of cables or bundles of wires will be supervised by dividing into groups of two sections, the two sections belonging to the same group being far from one another and remaining normally at the same temperature. In said cables or bundles are introduced detecting conductors the conductivity of which Widely varies with the temperature; said conductors may be insulated or not, and when several of them are provided in the same section they may be connected to each other in parallel or in series or not connected if it is desired to be warned of what part (inner or outer) of the cable has an abnormal temperature.

For wires disposed in sheaths, the detecting conductors are disposed inside when mounting, but for cables armored or not, said conductors must be placed inside during the manufacturing. Such a cable comprising detecting conductors further than the ordinary and eventually pilot wires, is a new product and constitutes one of the objects of the invention.

It may be noted that such detecting conductors may indicate a fault arising in the cable'because of the increase of temperature in consequence of a short circuit or a ground.

What claim is:

A system for indicating the accidental variations of temperature of groups of wires, comprising in combination a number of normally balanced Wheatstone bridges the branches of each of which are constituted by two resistances forming ratio arms and two loops of wire composed of a material the resistance of which varies with the temperature; each of said loops being arranged along one of the groups of the wires to be supervised, the two groups of wires corresponding to any one such bridge being relatively distant from one another and disposed in places the temperatures of which normally remain equal to each other; a source of electricity; a galvanometric relay having a movable member and contacts cooperating therewith, said relay having a winding for causing said member to move in one direction or another when energized, to make electrical connection with the corresponding contact; an alarm device for each bridge; another electric supply for said alarm devices, means for connecting said supply with said devices and with the movable member of the galvanometric relay; means including continuously rotating contactors for connecting the electric diagonals of each successive bridge to said source and to the winding of said relay respectively and simultaneously connecting the corresponding alarm device with the contacts of the relay whereby said relay is operated by the resulting potential difference when connected with a bridge which has become unbalanced, whereby upon operation of the relay the circuit of the alarm device corresponding to said unbalanced bridge is closed, to cause the alarm to operate.

REN JEAN JORDI. 

